This invention relates to an electrical connector having an insulator and at least one contact element fixed to the insulator and, in particular, to such an contact element used in the electrical connector and having multi-contact points to come into contact with a single mating contact element.
A first existing contact element of the multi-contact-point type is made of an elastic metal plate and comprises a fixing portion and an elastic portion extending from the fixing portion. The elastic portion is provided with an elongated hole formed at a position near to its one end and extending in a longitudinal direction thereof. A pair of contact points are formed on the elastic portion at both sides of the elongated hole. The contact points are brought into contact with a mating contact element in common.
A second existing contact element has two elastic finger portions which are formed by forming not the elongated hole but a slit in the elastic portion. The slit extends from the one end of the elastic portion towards the fixing portion so that the two elastic finger portions are in parallel with each other and symmetric to each other in relation to the slit. Two contact points are formed on middle positions of the two elastic finger portions, respectively. An example of the second existing contact element is disclosed in Japanese Examined Utility Model Publication (JP-Y) No. S56-5255 (5255/1981).
A third existing contact element has a bent finger portion formed at a intermediate position of the elastic portion in its extending direction by cutting and bending technique. Two contact points are formed on an end of the bent finger portion and an end of the elastic portion, respectively, so that the two contact points are located at offset positions in the extending direction of the elastic portion. An example of the second existing contact element is disclosed in Japanese Unexamined Utility Model Publication (JP-U) No. S61-44778 (44778/1986).
However, in the first existing contact, the contact points are synchronously displaced when they are brought into contact with a mating contact element. In other words, the contact points are not independently displaced with respect to each other. Therefore, if the mating contact is inclined or if the mating contact has an irregular surface, two contact points cannot follow the inclination or irregularity when the contact points are brought into contact with the mating contact. Thus, it is difficult to maintain a state where two contact points are reliably brought into contact with the mating contact.
In the second existing contact element, the two elastic finger portions are separated from each other by the slit. Therefore, two contact points formed on the finger portions are generally displaceable independently to each other so that they can be brought into contact with the mating contact element with independent contacting forces. Therefore, this second existing contact element has such a problem as in the first existing contact element.
However, the two elastic finger portions are same in material and have the same size, that is, similar in length, width and thickness. Therefore, two contact points are in contact with the mating contact element with the contacting forces equal to each other. On the other hand, two finger portions have the natural vibrating frequencies equal to each other. This results in that two elastic finger portions would simultaneously resonate to vibration applied thereto when the contact element is used under a condition where strong vibration and/or shock is applied to the contact element. This leads an undesired condition where electrical connection would be broken between the two contact points and the mating contact element.
In the third existing contact element, the contact points depend upon each other in behavior and each of the contact points is displaceable within a restricted range when they are brought into contact with the mating contact element. Specifically, the bent finger portion having one of the contact points is supported by the elastic potion having the other of the contact points. Therefore, a contacting force between one of the contact points and the mating contact element affects another contacting force between the other one of the contact points and the mating contact element. Therefore, it is difficult to maintain a stable and reliable contact between the contact points and the mating contact element.